New Monolith Stationary Phase for Microfluidic DNA Purification

Today, solid-phase extraction (SPE) is the most popular preparation method for the extraction and preconcentration of analytes. To obtain a high loading capacity, a large surface area of the solid phase is desired. Porous polymer monoliths are a new category of materials developed during the last decade. These materials are prepared using a very simple process in which a mixture of monomers and porogenic solvent is polymerized within a closed tuber or other container under carefully controlled conditions. Thus, the monoliths could be prepared into any shape. The polymerization mixture typically contains monomers, free-radical initiator, and porogenic solvent which affords macroporous materials with both large through-pores with a pore size of 1 to 20 nm and small meso-pore in 100-1,000 nm size range. The pore size can also be controlled over a broad range by different ratio of porogenic solvents. Since all the mobile phase must flow through the monolith, the mass transport within the monolith is dominated very much by convection, and the monolithic materials performed very well at high flow rates.

UV-induced photo-polymerization enables the accurate placement of monolithic matrices within the architecture of microscale devices, and the functional surface groups on the monomers allows for easy chemical modification of the surface. These methods have been used to create a high capacity, high efficiency silica-based DNA extraction monolithic column within a microfluidic device.